• Journal of the Korea Concrete Institute
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• v.25 no.2
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• pp.145-153
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• 2013

Recently, accelerated chloride diffusion coefficients are used for an evaluation of chloride behavior. Similar as apparent diffusion coefficients, accelerated diffusion coefficients decrease with time. In this study, decrease in diffusion coefficient with time is simulated with porosity. Utilizing DUCOM-program, porosities from 15 mix proportions are obtained and diffusion coefficients are modelled with regression analysis of porosity for 270 days. Considering non-linear binding capacity which means the relation between free and bound chloride ion, chloride behavior in high performance concrete is evaluated. Through utilizing the previous test results for concrete under chlorides for 180 days, the applicability of the proposed technique is verified. The proposed technique is evaluated to reasonably predict the chloride behavior in concrete with various w/c (water to cement) ratios and mineral admixtures (GGBFS and FA). It is also shown that decrease in chloride diffusion should be considered for chloride prediction in concrete with mineral admixture since it has very clear decrease in diffusivity with time.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.705-710
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• 2003

In this study, to confirm the diffusion coefficient of chloride ion is affected by the concentration of NaCl solution, capacity of voltage, time of an electric current, the diffusion coefficient of chloride ion in concrete was investigated through an electrochemical accelerated test. and the results of these test were compared with the diffusion coefficient of chloride ion by test of sodium chloride solution digestion. As the results of this study, the diffusion coefficient of chloride ion wasn't affected by the concentration of NaCl solution, capacity of voltage, time of an electric current within the range of this study and was similar to the diffusion coefficient of chloride ion by test of sodium chloride solution digestion.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.775-778
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• 1999

Accelerated chloride diffusion tests were carried out to estimate the chloride diffusion coefficient of concrete using ordinary portland cement, low heat belite-rich portland cement, and sulphate resistant portland cement. Concrete using low heat belite-rich portland cement showed a high diffusion coefficient due to delayed hydration of low heat belite rich portland cement, while the diffusion coefficients of concrete using sulphate resistant portland cement and ordinary portland cement were low.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.299-304
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• 2002

This research was to investigate the invasion and diffusion properties of chloride ion on the concrete containing mineral admixtures by the electrically accelerated test. Mineral admixtures selected in mixes were fly-ash, ground granulated blast-furnace slag, silica fume, and meta-kaolin with 3 degrees of replacement ratios. Tang and Nilsson's test method was used to estimate chloride diffusion coefficients of that mixes. As a result, the total current passing charge and the diffusion coefficient of chloride ion were reduced with the use of mineral admixtures and the increase of replacement ratios. In addition, compressive strength was related with diffusion coefficient of chloride ion. Diffusion coefficients of concrete mixed with ground granulated blast-furnace slag showed relatively low value under the range of compressive strength of 400㎏f/㎠.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.1-9
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• 2019

GGBFS(Ground Granulated Blast Furnace Slag), one of the representative concrete mineral admixtures, improves the long-term durability and engineering performance of concrete by latent hydraulic activity. In this study, considering 3 levels of W/B(0.37, 0.42, 0.47) and GGBFS replacement ratio(0 %, 30 %, 50 %), durability performances for chloride attack are evaluated, and equations which predict behavior of accelerated chloride diffusion are proposed. Also, the relationship between accelerated chloride diffusion coefficient and passed charge is evaluated. In target curing day, accelerated chloride diffusion tests(Tang's method, ASTM C 1202) and compressive strength(KS F 2405) are performed. In the 730 day's results of accelerated chloride diffusion coefficient, GGBFS concrete has up to 28 % of decreasing ratio compared to OPC concrete, and in those of passed charge, GGBFS concrete has up to 29 % of decreasing ratio compared to OPC concrete. Also, it is deemed that the impact of variation of W/B is less in GGBFS concrete than in OPC concrete. The equations which predict accelerated chloride diffusion coefficient and passed charge are drawn, based on the characteristics of mixture and test results. The equation which predicts passed charge shows slightly higher coefficient of determination than that which predicts accelerated chloride diffusion coefficient.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.973-976
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• 2008

Recently, it is increasingly reported that the deterioration of concrete structure under marine environments is due to diffusion and penetration of chloride ions. It is very important to estimate the diffusion coefficient of chloride ion in concrete. Estimation methods of chloride diffusivity by concentration difference is time-consuming. Therefore, chloride diffusivity of concrete is mainly conducted by electrically accelerated method, which is accelerating the movement of chloride ion by potential difference. However, there has not been any proper method for field quality control to closely determine the diffusion coefficient of chloride ion through accelerated tests using potential difference. In this paper, the various test methods for determination of chloride diffusion coefficient in concrete were investigated through comparison accelerated tests. From the results of estimated diffusion coefficient of chloride ion, relationship between the ponding test and acceleration test was examined.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.427-432
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• 1999

An electrci method for the rapid determination of chloride diffusion coefficient in concrete is proposed considering the electrical migration term in the Nernst-Plank equation. The experimental set-up for this method is basically that for PD index by Dhir, excluding some change in the experimental parameter values in consideration of reliability, simplicity and rapidity of the accelerated test method. Experimental results show that 30mm of specimen thickness, 10 volt of supplied potential, and 5M of chloride ion concentration are optimal

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.30-36
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• 2019

In order to evaluate service life of RC (Reinforced Concrete) structures exposed to chloride attack, chloride penetration analysis is required referred to the chloride diffusion coefficient from the actual mix proportions. In this work, accelerated diffusion coefficients are obtained from NT BUILD 492 and ASTM C 1202 and the related apparent diffusion coefficients are derived via the previously proposed relationship for RC structures near to sea shore. Considering the properties of the mix proportions and the most conservative analysis conditions like critical and surface chloride contents, service lifes in column and exterior wall member are evaluated through conventional program LIFE 365 ver.2. The different built-up period of 10 and 15 years has no significant effect on service life. The results from mix proportions with slag show longer than 75 years of service life with the help of higher time dependent parameter and lower initial diffusion coefficient.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.138-143
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• 2010

Recently, as many big marine concrete structures increase, it is necessary that chloride ion diffusion coefficient of concrete shall be evaluated but it will take a long time to evaluate chloride ion diffusion coefficient of concrete. Accordingly, many test methods are suggested to evaluate chloride ion diffusion coefficient in a short period time by the promotion in electro chemical ways but the systematic study for this is insufficient. Therefore, this study evaluates chloride ion penetration and diffusion features by three representative electric promotion tests targeting for three different cements whose ingredients are different and analyzes the correlationship between them. As a result, diffusion features of chloride ion varied according to the cement ingredients and three ingredients cement in which blast furnace slag powder and fly ash are mixed in constant ratio, which shows the most excellent cement diffusion properties. For diffusion properties of chloride ion, the correlationship between test methods are good.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.737-742
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• 2002

The chief factors for the penetration and diffusion of chloride ions in concrete are water-cement ratio(w/c), aging, thickness of cover concrete, chloride ions concentration of given environment, wet and dry conditions and etc. In this study, effect of w/c and aging on the characteristics of chloride ions diffusion in concrete were researched when environmental factors for the penetration and diffusion of chloride ions were constant. For this purpose, the voltages passing through the diffusion cell were measured by using accelerated test method using potential difference, and then diffusion coefficients of chloride ions by using Andrade's method were estimated for 44%, 49.5% and 55% of w/c, respectively. As a result, correlation among diffusion coefficients of chloride ions, w/c and aging were concluded through multiple regression model.